Introduction to Airspace
The National Airspace System (NAS) is a collection of United States airspace, air navigation facilities, services, airports, aeronautical charts, services, rules and regulations, procedures and technical information; as well as manpower and material. Below you will find the different airspace divided into different categories and types. Airspace is divided into Regulatory or Non-Regulatory airspace. Regulatory airspace has a set of specific regulations that govern that area. This will include Class A, B, C, D, E, G, Restricted Areas, and Prohibited Areas. Non-regulatory airspace is just used to advise or warn pilots of the operations that are conducted within the airspace. This will include Military Operations Areas (MOAs), Warning Areas, Alert Areas, and Controlled Firing Areas.
Within those 2 categories, there are 4 types of airspace. These 4 types are Controlled, Uncontrolled, Special Use, and Other airspace. Each unique sector of airspace is defined by its lateral and vertical boundaries. The lateral boundaries can be thought of are the airspace’s footprint along the ground. It can be as easy as just a circle around an airport but can get complex with many shapes and sizes. The vertical boundaries describe the upper and lower altitude limits. These altitudes can be labeled in one of 3 ways: Above Ground Level (AGL), Mean Sea Level (MSL), or Flight Level (FL).
You can use various different charts to determine which airspace you are flying through. Each type of airspace will have specific requirements that must be met in order to operate in that specific airspace. Some of the requirements can include pilot qualification requirements, weather requirements, speed requirements, aircraft equipment requirements, and others.
Special Use Airspace
Prohibited
Restricted
Warning Area
MOAs
Alert Area
Controlled Firing Areas
National Security Areas
Other Airspace
Wildlife & Recreational Areas
Terminal Radar Service Area
Airport Advisory Area & Services
Military Training Routes
Temporary Flight Restrictions
Parachute Jump Aircraft Area
Published VFR Routes
Class A Airspace
Class A airspace is also known as Class Alpha airspace. The easiest way to remember Class A airspace is by thinking “A for Above”. Class A is airspace that is above where small aircraft fly. Most aircraft that fly in Class A airspace are Commercial Airlines, Corporate Airplanes, and Military Jets.
Dimensions
Class A airspace generally begins at 18,000ft MSL and extends up to and including FL600, but does not include the airspace less than 1,500ft AGL. This extends over the 48 contiguous states (and Alaska) and within 12nm off the coast, as well as designated international airspace beyond 12nm within areas of domestic radio navigation signal or ATC radar coverage.
Operating Rules and Pilot/Equipment Requirements
Instrument Flight Plan
Instrument-Rated Airplane
Instrument-Rated Pilot
Two-Way Communication
Mode-C Transponder
DME measuring Equipped Airplane (Above FL240) - could be GPS
All person, unless otherwise authorized, must operate their aircraft IFR in Class A. So what does that mean? In very simple terms, that means that both the pilot and aircraft will need to be instrument rated and be on an IFR flight plan. There is NO VFR flying allowed. Within Class A airspace, the aircraft must be equipped with a two-way radio (and you must remain two-way communication with ATC) and an altitude reporting transponder (Mode C). You will need a clearance from ATC before you are permitted to enter Class A airspace. This airspace is controlled by an ARTCC (Air Route Traffic Control Center) AKA “Center”. If you are navigating with the use of VORs, DME will be required above 24,000ft MSL. Also, keep in mind, after Jan1st, 2020, ADS-B will be required.
When you are operating in Class A airspace (Above 18,000ft), make sure you change your altimeter setting to standard atmospheric pressure, which is 29.92.
SPEED LIMIT
The only speed limit in Class A Airspace is to remain slower than the speed of sound, which is Mach 1.
WEATHER MINIMUMS
There are no specific weather requirements in Class A airspace due to all aircraft being required to be on an IFR Flight Plan. You can get more in-depth information by clicking VFR Weather Minimums.
Chart Depiction
Class A will not be depicted on any charts. This makes sense if you think about it. The lateral boundaries are usually the parts that are depicted via outlines on a chart. Since Class A airspace exends over the entire 48 contiguous states (and Alaska), there wouldn’t be anything to depict.
Class B Airspace
Class B airspace is also known as Class Bravo airspace. Class B airspace surrounds the nation’s busiest and largest airports. Class B Airspace surrounds those airports that have at least an operational Air Traffic Control Tower (ATCT) and Terminal Radar Approach Controls (TRACON).
Dimensions
Lateral distances of bravo airspace will vary with the local area, but will typically maintain a shape of an upside-down wedding cake. Vertically, the airspace is usually from the surface of the airport up to 10,000ft MSL, with some exceptions. The configuration of each Class B airspace area is tailored for each airport and consists of a surface area and two or more layers.
Operating Rules and Pilot/Equipment Requirements
The pilot must be at least a Private Pilots (or a student pilot with endorsement from CFI)
There are 12 airports around the country that student pilots are never authorized to enter (even with endorsement) and those airports can be found in the AIM under section 3-2-3.
Two-Way Communication
Clearance to Enter
Mode-C Transponder
You must have an ATC clearance prior to entering Class B airspace. All aircraft within the airspace will receive separation services provided by ATC.
SPEED LIMIT
WEATHER MINIMUMS
In Class B airspace, you must remain “Clear of Clouds”. You can get more in-depth information by clicking VFR Weather Minimums.
Chart Depiction
Class B airspace is depicted on charts with solid blue lines. Inside each sector of lateral airspace depiction, you will find numbers that give you the vertical dimensions.
References
FAR 91.131
AIM 3-2-3
PHAK Chapter 15
Class C Airspace
Dimensions
Operating Rules and Pilot/Equipment Requirements
SPEED LIMIT
WEATHER MINIMUMS
Chart Depiction
Class D Airspace
Dimensions
Each Class D airspace is Class D airspace usually extends from the surface to 2,500ft above field elevation (MSL).
Operating Rules and Pilot/Equipment Requirements
SPEED LIMIT
200kts within the Class D airspace
WEATHER MINIMUMS
Chart Depiction
Class E Airspace
Dimensions
Operating Rules and Pilot/Equipment Requirements
SPEED LIMIT
WEATHER MINIMUMS
Chart Depiction
Class G Airspace
Class G Airspace the only uncontrolled airspace. Although ATC has no authority or responsibility to control air traffic, pilots should remember there are visual flight rule (VFR) minimums that apply to Class G airspace. No formal separation services are provided, so it is the responsibility of the pilot to see and avoid other aircrafts.
Dimensions
Class G Airspace is the portion of airspace that has not been designated as Class A, Class B, Class C, Class D, or Class E. Think of Class G as being a filler. It fills in all the gaps in airspace that have not been designated as any of the previously mentioned controlled airspaces. Class G is considered to be an uncontrolled airspace, meaning that ATC does not have any jurisdictions.
Operating Rules and Pilot/Equipment Requirements
To fly in Class G airspace, you will need a minimum of a student pilot certificate. When flying into an airport in Class G airspace, communications should be established prior to 4 NM from the airport, up to and including 2,500' AGL. There is no formal separation is provided, so each pilot is responsible to “see and avoid” other traffic. Remember to follow any noice abatement procedures, which can be found in the airport page under airport remarks as NS ABTMT.
SPEED LIMIT
250 knots below 10,000 MSL
WEATHER MINIMUMS
Chart Depiction
Class G will not be depicted on the charts. As we said before, it is sort of a "filler airspace". So how do we know where it is, if it's not depicted? That's easy, just look at the VFR sectional and find all the depicted airspaces, Class G will be everything else.